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I've got lenovo ideapad Y530. According to dmidecode, I should have 3GB RAM:

tomasz@tomasz-lenovo-ideapad-Y530:~$ sudo dmidecode --type memory
[sudo] password for tomasz: 
# dmidecode 2.9
SMBIOS 2.4 present.

Handle 0x0023, DMI type 16, 15 bytes
Physical Memory Array
        Location: System Board Or Motherboard
        Use: System Memory
        Error Correction Type: None
        Maximum Capacity: 4 GB
        Error Information Handle: No Error
        Number Of Devices: 2

Handle 0x0026, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: 0x0027
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 2048 MB
        Form Factor: SODIMM
        Set: None
        Locator: DIMM0
        Bank Locator: BANK0
        Type: DDR2
        Type Detail: Synchronous
        Speed: 667 MHz (1.5 ns)
        Manufacturer: Manufacturer0
        Serial Number: SerNum0
        Asset Tag: AssetTagNum0
        Part Number: PartNum0

Handle 0x0029, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: 0x002A
        Total Width: 64 bits
        Data Width: 64 bits
        Size: 1024 MB
        Form Factor: SODIMM
        Set: None
        Locator: DIMM1
        Bank Locator: BANK1
        Type: DDR2
        Type Detail: Synchronous
        Speed: 667 MHz (1.5 ns)
        Manufacturer: Manufacturer1
        Serial Number: SerNum1
        Asset Tag: AssetTagNum1
        Part Number: PartNum1

But top shows me I've got 2,5GB:

top - 23:32:07 up  5:49,  3 users,  load average: 2.84, 1.71, 1.42
Tasks: 206 total,   7 running, 199 sleeping,   0 stopped,   0 zombie
Cpu(s): 44.4%us,  7.9%sy,  0.0%ni, 45.2%id,  2.4%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   2547380k total,  2290924k used,   256456k free,   150608k buffers
Swap: 24411132k total,    80652k used, 24330480k free,   457716k cached

Does anyone know what's going on (where is the 0,5GB missing)?


PS a friend of mine told me to run:

sudo sync
sudo echo 3 > /proc/sys/vm/drop_caches

in this case, but I don't know what it does and therefore I'm not sure about that... but

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This looks like it uses integrated graphics. If you check the bios, how much RAM are you giving to the graphics card? –  Paul Dec 3 '13 at 22:45

1 Answer 1

up vote 2 down vote accepted

My guess would be that half a gig of memory is being shared to the video card.

dmidecode is reporting the information the DIMMs themselves are reporting, so you've got a 2GB and a 1GB module in the system.

top is reporting what the OS sees and can use.

One way you could try and verify this is to go into your BIOS - for systems where memory is shared to video, there's usually an option to set how much of the memory is allocated to video.

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This makes sense, since my laptop model was supposed to be a high-performance multimedia machine. Do you know which sections to look in bios? –  tkoomzaaskz Dec 3 '13 at 22:46
    
Nope . . . I did a quick google search for the Y530, and it looks like some of the cheaper models had integrated Intel video, while the more expensive had discrete Nvida cards (which would not share memory). It appears that you've likely got the integrated video . . . –  ernie Dec 3 '13 at 22:48
    
I do have the nVidia, VGA compatible controller: nVidia Corporation G98 [GeForce 9300M GS] (rev a1) (prog-if 00 [VGA controller]) from lspci. –  tkoomzaaskz Dec 3 '13 at 22:56

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